The invention relates to a reference voltage source for supplying a reference voltage.
In the general state of the art it is common practice to use a so-called band gap voltage reference circuit as a reference voltage source. The reference voltage is then determined by the sum of a diode voltage and a voltage across a resistor. The diode voltage has a negative temperature coefficient which is compensated by a positive temperature coefficient of the voltage across the resistor.
A disadvantage of conventional band gap voltage reference circuits is that they comprise resistors of comparatively large value, which resistors should be matched in value with each other. Particularly in IC processes, in which it is difficult or not possible to fabricate resistors which are accurate and have comparatively high resistance values, said disadvantage is a very significant factor. As a result, there is a need for band gap voltage reference circuits in which the positive temperature coefficient necessary for compensation of the negative temperature coefficient of the diode voltage is realized in another manner.